茶皂素对污染土壤中重金属的修复作用

采用振荡离心的方法研究了生物表面活性剂茶皂素在不同浓度、pH值和离子强度下对污染土壤中重金属去除效果的影响;并采用BCR法研究了茶皂素处理前后土样中各形态的重金属含量变化。试验结果表明:随着茶皂素浓度的增加,重金属的去除率随之增加,在茶皂素浓度为7%时,对供试土样中重金属的去除率达到最大值,去除率分别为Cd 96.36%,Zn 71.73%,Pb 43.71%,Cu 20.56%;随着土壤环境pH值的增加,重金属的去除率随之减少,适宜的pH范围在5.0左右;离子强度对Pb,Cu的去除效率影响不大,Zn,Cd的去除率随着离子强度的增加而减少。比较茶皂素处理前后土样中重金属各形态含量的变化,发现酸溶态的重金属更易被茶皂素去除,其次为可还原态、可氧化态和残渣态的重金属很难被去除。

Removal of Heavy Metals in Contaminated Soils with Tea Saponin

This paper reports the efficiency of a biosurfactant tea-saponin on removing heavy metal from contaminated soils.Batch experiments were performed to test the influence of tea-saponin concentration,pH and ionic strength on the removal efficiency.The results showed that the removal efficiency of heavy metals could be enhanced with the increase of the added tea-saponin concentrations.By adding 7% of tea-saponin,the removal efficiency of heavy metals in the tested soil samples can reach the maximum and could finally reach 96.36%,71.73%,43.71% and 20.56% for Cd,Zn,Pb and Cu respectively.The removal efficiency gradually decreased with the increase of pH values.The suitable pH scope should about 5.0.The ionic strength slightly had a negative influence on the removal efficiency of Zn,Cd,but no efforts on Pb,Cu.Comparing the transformation of heavy metals' chemical forms before and after tea-saponin treatment by BCR method,it was found that heavy metals in acetic acid extractable fraction are more easily to remove,the second is hydroxide-bound fraction,heavy metals in organically-bound fraction and residual fraction are difficult to remove.